Some difficulties were encountered installing this extension on php 5.1.6. 're2c' was not found. On Fedora Core 5, php 5.1.6, I had to...
Install gc++ as re2c requires C++ and will not compile with the standard C compiler most often used.
Download re2c from sourceforge, untar, configure, make, make install.
Download pxlib from sourceforge, untar, configure, make, make install.
pecl install paradox (it has been moved from pear)